The present invention relates to compounds that are useful as catalyst components. More particularly the present invention relates to such compounds that are particularly adapted for use in the coordination polymerization of unsaturated compounds comprising an anion containing at least two Lewis basic sites derived from certain inorganic or organic Bronsted acids, which are coordinated to Lewis acids. Such compounds are particularly advantageous for use in forming supported polymerization catalysts wherein at least the catalyst activator is chemically attached to a substrate material.
It is previously known in the art to activate Ziegler-Natta polymerization catalysts, particularly such catalysts comprising Group 3–10 metal complexes containing delocalized π-bonded ligand groups, by the use of Bronsted acid salts capable of transferring a proton to form a cationic derivative or other catalytically active derivative of such Group 3–10 metal complex. Preferred Bronsted acid salts are such compounds containing a cation/anion pair that is capable of rendering the Group 3–10 metal complex catalytically active. Suitable activators comprise fluorinated arylborate anions, such as tetrakis(pentafluorophenyl)borate. Additional suitable anions include sterically shielded diboron anions of the formula:
wherein:
S is hydrogen, alkyl, fluoroalkyl, aryl, or fluoroaryl, ArF is fluoroaryl, and X1 is either hydrogen or halide, disclosed in U.S. Pat. No. 5,447,895. Additional examples include carborane compounds such as are disclosed and claimed in U.S. Pat. No. 5,407,884.
Examples of preferred charge separated (cation/anion pair) activators are ammonium, sulfonium, or phosphonium salts capable of transferring a hydrogen ion, disclosed in U.S. Pat. Nos. 5,198,401, 5,132,380, 5,470,927 and 5,153,157, as well as oxidizing salts such as ferrocenium, silver or lead salts, disclosed in U.S. Pat. Nos. 5,189,192 and 5,321,106 and strongly Lewis acidic salts such as carbonium or silylium salts, disclosed in U.S. Pat. Nos. 5,350,723 and 5,625,087.
Further suitable activators for the above metal complexes include strong Lewis acids including tris(perfluorophenyl)borane and tris(perfluorobiphenyl)borane. The former composition has been previously disclosed for the above stated end use in EP-A-520,732, whereas the latter composition is similarly disclosed by Marks, et al., in J. Am. Chem. Soc., 118, 12451–12452 (1996).
In WO99/42467, WO01/23442 and WO02/08303 expanded ionic catalyst activators are disclosed that are well suited for use as olefin polymerization activators.
Despite the satisfactory performance of the foregoing catalyst activators under a variety of polymerization conditions, there is still a need for improved cocatalysts for use in the activation of various metal complexes especially under a variety of reaction conditions. Accordingly, it would be desirable if there were provided compounds that could be employed in solution, slurry, gas phase or high pressure polymerizations and under homogeneous or heterogeneous process conditions having improved activation properties.